How to reduce the wear of the screw of the injection molding machine?

Update:29 Jan 2021

The injection screw is the core component of the injection molding machine, and the screw has been working under high temperature, high pressure, high mechanical torque and high friction environment for a long time, and the wear problem is inevitable. Generally, the screw has undergone surface nitriding treatment to improve the surface hardness, that is Improve wear resistance.

However, if the cause of wear is ignored and the wear is not minimized, the working life of the screw will be greatly reduced.

1. screw barrel for Injection molding machine temperature setting: Each plastic has an ideal plasticizing temperature range, and the barrel processing temperature should be controlled to make it close to this temperature range.

Granular plastic enters the barrel from the hopper and first reaches the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are not heated enough and melted unevenly, it is easy to increase the abrasion of the inner wall of the barrel and the surface of the screw.

Similarly, in the compression section and the homogenization section, if the molten state of the plastic is disordered and uneven, it will also cause increased wear.

2. Setting of screw speed: Because some plastics are added with strengthening agents, such as glass fiber, minerals or other fillers. The friction of these substances on metal materials is often much greater than that of molten plastics.

When injection molding these plastics, if they are made with a high rotation speed, it will increase the shearing force to the plastic, and at the same time, the reinforcement will produce more shredded fibers. The shredded fibers contain sharp ends, causing wear Power is greatly increased. When inorganic minerals slide at high speed on the metal surface, their scraping effect is not small. Therefore, the speed should not be adjusted too high.

3. Sundries in plastics: The production with pure raw materials may have relatively lower risks. However, in order to reduce costs, companies generally add some nozzle materials to the raw materials. Due to some on-site management reasons, the nozzle materials are easy to mix during crushing. Into some small metal chips, this is very harmful to the screw, so the magnet holder is generally installed in the barrel to strictly manage and monitor the feeding.